Does type checking for all context property sets. (issue4654090)

[mtsolo]

Reviewers: ,

Message:
I tried this with my local branch and I noticed no slow-down (I'm sure
there is one, but it certainly is not prohibitive).  It gets rid of any
potential segfaults from bad property sets in the layout block.

I realize now that all \set calls are, in fact, events and thus go
through a different function (set_property_from_event) that does this
type checking.

Cheers,
MS

Description:
Does type checking for all context property sets.

Please review this at http://codereview.appspot.com/4654090/

Affected files:
  M lily/context.cc


Index: lily/context.cc
diff --git a/lily/context.cc b/lily/context.cc
index  
4dbb6e5657721e436dc4f52227d24409c62a53e8..5ade53aa8ef1290cecedffff3e790bb9c1b8ff53  
100644
--- a/lily/context.cc
+++ b/lily/context.cc
@@ -490,10 +490,10 @@ Context::instrumented_set_property (SCM sym, SCM val,  
const char*, int, const ch
 void
 Context::internal_set_property (SCM sym, SCM val)
 {
-  if (do_internal_type_checking_global)
-    assert (type_check_assignment (sym, val, ly_symbol2scm  
("translation-type?")));
+  bool ok = type_check_assignment (sym, val, ly_symbol2scm  
("translation-type?"));

-  properties_dict ()->set (sym, val);
+  if (ok)
+    properties_dict ()->set (sym, val);
 }

 /*